A popular method to implement low frequency filters on integrated circuits is to use operational amplifiers with feedback networks constructed from resistors and capacitors. Filters of this type are generally known as active RC filters. In an ideal world the filter response would be defined purely by the resistor and capacitor values, and the gain of the operational amplifier will always be sufficiently high, irrespective of filter operating frequency, to have a negligible effect on the filter response.
Whilst it is relatively easy to make operational amplifiers having a sufficiently high gain and bandwidth for the operational amplifier to have negligible effect on the filter response, this is generally at the expense of power consumption. Power consumption gives rise to excess heat generation, and in the context of battery powered portable devices, such as mobile telephone handsets, excess current consumption which reduces the time interval between having to recharge the battery. Allowing the unity gain bandwidth to drop causes increased ripples and peaks in the filter response compared to the ideal response.